The invention concerns a rear axle suspension for vehicles, especially automotive vehicles, with independently suspended wheels that are braced by torsion spring elements against a bolster, whereby the bolster is elastically connected with the vehicle frame or body.
It is known (German Pat. No. 1,117,016) that shocks coming from the roadway can be damped via an auxiliary frame elastically suspended on the vehicle body, the wheels being suspended on the said frame. Moreover, a wheel suspension for automotive vehicles is known (German AS 1,265,598) wherein the wheels are independently braced against a bolster via a torsion bar spring, the said bolster again being connected via elastic rubber cushions with the body of the vehicle. In such an arrangement, all elastic elements between the body or frame and the bolster are fractionally loaded with the weight of the vehicle and must therefore be designed for damping of vibration and also for acceptance of weight. In addition, the frame and the bearings (German Pat. No. 1,177,016) entail a space requirement which is not available in the case of small low vehicles, e.g. sports cars. In these known embodiments of a bolster, stable guiding of the wheel is not ensured, because of the elasticity of the bearings in the longitudinal and transverse direction of the vehicle.
The present invention therefore is intended to provide a bolster that offers optimal damping of the roll noise with stable travel and structurally simple bearings and bolster parts, whose dispostion in the vehicle yields favorable conditions with respect to the space requirements for placement of the bolster.
This problem is solved according to a preferred embodiment of the invention in that the bolster comprises two supports running in the longitudinal direction of the vehicle, whereof, seen in the direction of travel, the forward support is made as a rigid part and is braced on the vehicle body via elastic bearings so as to be insulated against vibration, and the rear support consists of a spring member that is elastic in the transverse direction of the vehicle and is connected with the vehicle body via an elastic bearing, to take up vibration and torque.
According to another characteristic of the invention, a rigid longitudinal support presents a seat for a transverse axle pipe as well as, seen in the direction of travel, the forward guide bearing and the rear thrust bearing. The rear thrust bearing of the longitudinal support, according to a feature of the invention, is relatively unyielding, to receive forces in the transverse direction of the vehicle.
Another feature of the invention provides that, between the vehicle body and the longitudinal support, there be an elastic element which has greater elasticity vertically or almost vertically than it has in the horizontal or almost horizontal direction, crosswise to the longitudinal axis of the vehicle. Moreover, it is provided according to an embodiment disclosed with respect to the invention that the spring member, seen in the direction of travel, is connected to the transverse axle pipe at its forward end, and with the vehicle body at its rear free end via a thrust bearing. The thrust bearing is disposed on the free end of the spring member above the wheel axle and about in the perpendicular midplane of the wheel. Further, it is provided according to the invention that the thrust bearing presents an elastic element which is more elastic in the longitudinal and transverse directions of the vehicle than in the vertical direction. The arrangement of the rear axle suspension offers the advantage of a vibration-insulated fixation of the rear axle on the vehicle body, whereby roll noise is substantially reduced and the travel behavior of the motor vehicle remains unaffected by negative disrupting moments in case of peripheral and lateral forces. Moreover, a structurally simple construction and arrangement of the bolster is achieved, which can be built into a car even supplementarily, and which is space-saving, not reducing trunk and/or interior space. The bolster has the additional advantage that by its construction there can be a division of functions so that one bolster part (the longitudinal support) or the guide and thrust bearing between this bolster part and the vehicle body can be called on only for vibration insulation and guiding, and be relieved of the other forces or the weight of the body, while the other bolster part (the spring member) or the support bearing can be used for the preponderant receiving of the torque of the torsion bar spring or the weight of the body and for vibration insulation as well. In this way, essentially the bearings that are solely vibration insulating can be made very soft in the direction that receives the vibration. Thus, by a separation of functions there is avoidance of a great outlay in construction. Hereby, only one more bearing on the spring member is necessary, through which the forces of the body or the torque of the torsion bar spring will be taken up.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a single embodiment in accordance with the present invention.